This document will more specifically describe the problem in the field of electrical cables, with which the inventors of this patent application have been faced. The invention is of course not limited to this particular field of application, and is of interest for any type of cable involving a similar problem (for example, optical cables).
Traditionally, an electrical cable comprises a protective sheath wherein one or more electrical conductor(s) is (are) housed. This protective sheath is intended to ensure the isolation of electrical conductors from the external environment.
There are currently a very wide variety of cables that have been developed to respond to a wide range of applications, which must be capable of being easily identified.
The need to visually distinguish one cable from another among a plurality of cables is therefore a problem with which the manufacturers and users of cables are commonly faced.
For this reason, numerous identification systems (or indicators), such as, for example, identification by labeling, by a writing field or by a color code, have been envisaged so as to facilitate the identification of cables. Usually, the cables are marked in relief or with ink on their external sheath.
Various techniques for identification by color code are known from the prior art.
For example, a known technique, presented in patent document GB 260,837, consists of permanently attaching a colored polymer or plastic indicator strip on one or more arc portions of the external surface of the protective sheath of an electrical cable. The color of the colored plastic or polymer indicator strip is assigned according to characteristics of the cable.
Another known technique presented in patent document U.S. Pat. No. 2,521,123 (Western Electric) is based on a manufacturing technique by sheath extrusion of the protective sheath of an electrical cable consisting of forming, during the extrusion phase, an indicator strip made of a colored polymer material, at the protective sheath.
The IrisTech™ technique, developed by the Prysmian company and described for example in the brochure entitled “Cabo Eprotenax Gsette® EPR 0.1/1 kV” is also known. This technique consists of producing, by sheath extrusion, a cable of which the protective sheath comprises a longitudinal indicator strip, which constitutes a portion of the surface of the sheath of the cable. The strip is part of the protective sheath and therefore cannot be detached (unless excessive force is used and unless the circular cross-section of the cable is altered). The strip has a light color different from that (generally black) of the rest of the surface of the protective sheath. The strip is such that, on top of it, a user can write (with a pencil of the type used to write on CDs) information useful for the installation or subsequent maintenance of the electrical assembly wherein said cable is used. Owing to a predetermined color code, the color of the strip indicates the electrical cross-section of the cable (for example, a distinct color for each cross-section possible between 1.5 and 25 mm2).
None of the known techniques mentioned above proposes that the indicator strip (colored strip) can be detached from the protective sheath. Indeed, according to the known techniques, the indicator strip is permanently and irremovably attached to the protective sheath, so that the removal of this indicator strip would cause a deformation, and even tearing of the protective sheath, causing an irremediable alteration of the protective sheath and, in particular, a change in the external diameter of the sheath. The cable therefore would no longer have a circular cross-section and would very likely be non-standard.
However, the fact that the indicator strip is permanently and irremovably attached to the protective sheath has disadvantages:
if the user wants to change or remove the initial identification of a cable, provided by the indicator strip, it is not possible. For example, the user may want to use an identification of the cables only during the installation phase of the cables;
the use of a permanent and irremovable indicator strip is not possible for all cables because, in certain countries, there is a single required sheath color (for example, standard NF C 32-321 requires an entirely black sheath).